Ligand K-edge XAS studies are proposed as a probe of the electronic structure of complexes containing open-shell metal ions. Preliminary results have shown that by studying the ligand edge structure, it is possible to quantitatively probe the covalency of the bond between the ligand and the metal center, and to differentiate the mode of bonding, specifically bridging vs. terminal liganding, between inequivalent atoms of the same kind in a metal center. The proposed research will first focus on developing a detailed understanding of how sulfur and chlorine K-edge XAS edge features are related to the electronic and geometric structure of Cu and Fe metal centers.